1. Field of the Invention
This invention relates generally to an integrated real and virtual manufacturing automation system that employs a programmable logic controller that controls part flow between a real machine in a real world part of the system and a virtual machine in a virtual world part of the system and, more particularly, to an integrated real and virtual manufacturing automation system that employs a programmable logic controller that controls part flow between a real machine in a real world part of the system and a virtual machine in a virtual world part of the system using virtually coupled sensors and actuators.
2. Discussion of the Related Art
Various approaches are known in the art for testing and debugging manufacturing automation systems and processes. One approach is referred to as a traditional field test where testing of new physical equipment using existing systems can be achieved by either setting up a duplicate testing purpose only system or using the existing system in the plant. While there is excessive cost associated with creating and maintaining a duplicate testing purpose only system, testing using the plant requires interrupting current production. Also, the field testing is not feasible when the new physical equipment is unobtainable.
Another approach is referred to virtual commissioning that includes testing with emulated systems and components. By using the emulated or simulated system and components, virtual commissioning enables reasonable accuracy and greater efficiency of validation allowing for many test scenarios that would not be possible at the installation site without adding significant deployment time and cost. Specifically, for virtual commissioning of manufacturing automation controls, the control logic is tested on a virtual model of the system or a station before actually being built, thus greatly reducing the time required for field testing. However, virtual commissioning hinges on the completeness and accuracy of the virtual model of the system and components. In particular, the modeling fidelity of each automation component, such as the PLC, I/O block, sensors/actuators, network, wiring and HMI, has a direct impact on the validity of the virtual commissioning results. Furthermore, creating a 100% complete and accurate virtual environment is not likely to be realized in the near future.
The third potential approach is referred to as a hybrid emulation environment. The hybrid emulation environment is comprised of virtual emulated models and real physical system components whose virtual model is not readily available. During the manufacturing process, the manufacturing automation system moves the part from one manufacturing station to another manufacturing station while performing certain manufacturing activities, such as welding, to the part. When a part is moved from a station in the virtual world to another station in the physical world, the part has to be presented to the physical station so that the physical station may function properly. In the contrast, when a part is moved from a physical work-station to a virtual work-station, the physical part has to be properly handled in the real world and its transfer presence to the virtual world has to be effectively communicated to the virtual world.
As discussed above, it is known in the art to simulate manufacturing or other processes prior to implementing the process so that engineers and technicians can ensure that the process will operate adequately and efficiently as intended. One technique for simulating such a process includes emulating the process in the virtual world using algorithms on a computer system.
It is sometimes not possible to provide a realistic virtual model of a particular robot or other machine that the engineer wants to test. There are many reasons as to why a particular machine cannot be accurately modeled, including trade secret information of the particular machine from the manufacturer. In these situations, it is desirable to provide a hybrid environment of the manufacturing cell, where certain portions of the cell are provided in the virtual world and those machines that cannot be virtually modeled are provided as real devices in the process.
Current virtual emulation approaches require extensive model development that requires costly engineering time and software investment. Emulation is increasingly used for virtual testing of complex automation systems, but it cannot guarantee the complete correctness of a given automation system because of the inaccuracies in a particular model. The development of simulation models requires additional time and engineering expertise. Highly accurate model development is time consuming, expensive and sometimes not possible. Field testing and debugging requires the availability of new equipment and access to deployed automation systems that may result in costly regular production shutdown.